1. Field of the Invention
The present invention relates to oral compositions. More particularly, the present invention relates to oral compositions which provide substitutes for, or augmentation of natural saliva.
2. Description of the Prior Art
For millions of Americans dry mouth is a chronic disorder which may lead to numerous health, nutritional, and social hazards. Sores often develop in dry areas inside the mouth of those afflicted. Speech may become strained and painful, which may lead sufferers to withdrawal from social contact. Even eating, drinking, and breathing become difficult tasks. The inability to enjoy a standard of living taken for granted by most may further cause disillusionment and depression.
In the article "When the mouth runs dry" Tufts University Diet & Nutrition Letter, April 1991, Vol. 9, No. 2, pp. 7-8, it was disclosed that, over the course of several days, a group of senior citizens with dry mouth were eating foods lower in 12 nutrients ranging from vitamin A to thiamin than a group without the problem. Particularly lacking in their diets were potassium, vitamin B6, iron, calcium, and zinc as well as fiber. A reason suggested by this reference for less healthful eating is that the parched, crusty, and sensitive conditions dry mouth creates can hamper the ability to tolerate spicy or acidic foods.
Other foods, such as breads, cereals, and some fruits and vegetables, can also be difficult to chew and swallow because of a lack of saliva to moisten them. It was also found that people with dry mouth often perceive the taste and quality of their food to be poor in general, and that curbs their appetite and blunts overall interest in eating.
An even more acute problem is that serious dry mouth may make it very difficult to consume fluids. Water itself may become painful to swallow in sufficient quantity to avoid rapid dehydration. Xerostomia, the chronic condition of dry mouth, accordingly feeds on itself, leading to progressively more serious health hazards.
Atkinson, et al in "Salivary gland dysfunction: causes, symptoms, treatment," Journal of the American Dental Association, April 1994, Vol. 125, No.4, pp. 409-416, disclose that salivary gland dysfunction can also contribute to tooth decay, even in patients with good oral hygiene. Saliva protects teeth from acidic foods and also contains antibodies and other substances that protect against disease-causing organisms.
Yet another complication which arises from lack of natural saliva is a shift in systemic pH balance beyond the oral cavity. Korsten, et al. report in "Chronic xerostomia increases esophageal acid exposure and is associated with esophageal injury.", American Journal of Medicine, June 1991 Vol. 90, No. 6, pp. 701-706, that the esophagus, the connection between the pharynx and stomach, is sensitive to acids produced in the stomach. The acids can cause esophagitis when the acids are not cleared promptly.
Esophageal acid is cleared by swallowing and saliva. Reported results from monitoring the acidity of the esophagus revealed significant abnormalities in xerostomic subjects. Esophageal acid clearance was clearly delayed when saliva production was artificially inhibited by atropine or when saliva delivery into the esophagus was abolished by aspiration. It was found that patients with xerostomia accordingly had delayed esophageal acid clearance and abnormal 24-hour esophageal pH and were likely to have histologic and clinical evidence of esophagitis, which can lead to esophageal injury.
There are numerous factors which can lead to chronic dry mouth. In xerostomic individuals, saliva production is sharply or completely curtailed. Medications with anticholinergic activity can reduce salivary gland function. These include prescription drugs such as antidepressants and antipsychotics, and common over the counter drugs such as antihistamines. Xerostomia is a potential side effect of more than 250 drugs, including PROZAC, XANAX, DYAZIDE, ACTIFED, and ibuprofen as found in ADVIL, MOTRIN and NUPRIN.
Radiation treatments, microbial infections, and Sjogren's syndrome are other major causes of salivary gland dysfunction. Radiation therapy for mouth and throat cancers can destroy salivary function completely. Often, there is little choice but to undergo treatment which sacrifices normal salivary gland function. There is no known cure for radiation induced xerostomia. Accordingly, patients which undergo radiation therapy of the head, neck, and/or upper chest to enhance survival from serious maladies such as cancer usually suffer xerostomia as a condition of living.
Treatments for salivary gland dysfunction have met with limited success in the prior art. Indications may include use of artificial saliva or saliva-stimulating agents, although neither had been found to be universally effective. Artificial saliva products, which may provide temporary relief, are available under the trade names XERO-LUBE, OREX, SAL-ESE, SALIVART, and MOI-STIR. These products typically are compositions of carboxymethylcellulose and mineral salts. Other treatments often include contradictory recommendations such as: 1) eating foods with strong tastes, 2) avoiding spicy foods, 3) lubricating the mouth with a layer of oils, petroleum jelly, or butter, and 4) keeping the mouth thoroughly clean with vigilant brushing and rinsing.
Artificial saliva compositions have also been the subject of earlier patents. For example, artificial saliva compositions using a polysaccharide base are disclosed in U.S. Pat. No. 5,260,282 to Attstrom et al. Another artificial saliva composition, based on chitins and/or chitosans, is disclosed by U.S. Pat. No. 4,879,281 to Shibasaki et al. U.S. Pat. No. 3,767,789 to Rankin discloses a synthetic mucus composition which forms in vivo when a polyalkylene oxide solution is applied thereto.
Glycerin is of course a well known compound which has been used orally. "When your mouth goes dry," Consumer Reports Health Letter, August 1990, Vol. 2, No. 8, pp. 61-62, discloses that glycerine may be added to warm water to provide an oral lubricant. A composition for oral use which includes various flavors and preservatives is disclosed by U.S. Pat. No. 4,887,620 to Summers. This composition may be encapsulated in a glycerin containing gel.
Various conventional oral uses for glycerin are discussed by Martindale, The Extra Pharmacopoeia, 29th Edition, Reynolds, ed., 1989, pp. 1128-1130; and The Merck Index of Chemicals and Drugs, 7th Edition, Stecher, ed., 1960, pp. 489-490. These include the use of glycerin for reducing intra-ocular and intra-cranial pressure, as well as a lubricant, emollient, and sweetener for other drugs such as expectorants. The Martindale reference cautions that glycerin (or glycerol) may cause dehydration.
None of the above disclosures or patents, taken either singly or in combination, is seen to describe the instant invention as claimed.